Field of the Invention
The present invention relates to a motorcycle including a water pump forming a cooling system of an internal combustion engine. (In this application, it is simply called an “engine”.)
Description of the Related Art
A water-cooled engine mounted on a motorcycle is equipped with a water pump forming a cooling system of the engine. In the cooling system of the engine, the water pump leads cooling water to a radiator through a cooling water passage provided in a cylinder, a cylinder head, and so on. The cooling water cooled in the radiator is returned to the water pump again.
As a motorcycle of this type, Patent Document 1, for example, discloses a structure in which a water pump is disposed on a lower portion of an engine (on a right side of a crankcase) and the water pump is coupled to a crank of the engine to be driven.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2007-40297
However, providing the water pump on the crankcase accordingly increases the size of the crankcase.
Further, if the water pump is provided on the crankcase, cooling water pipes connecting the water pump to a radiator and a cylinder need to extend up to the crankcase located on a lower portion of a vehicle body. Accordingly, the cooling water pipes extend up and down around the engine, and in particular in a vehicle having an exposed engine, the cooling water pipes are exposed, which spoils the beauty of the outer appearance. Further, when the cooling water pipes become long, a volume of the cooling water accordingly increases.